Installing on Ubuntu using Kamal's PPA on "launchpad"

And you are done. Fldigi will be installed and a new item added
to your window manager's applications menu. Once you've added
the PPA, you will automatically get updated versions from the PPA as well, along with regular system package updates.

The PPA fldigi .deb packages install the executable at /usr/bin/fldigi.

More specifically, the PPA packages are simply "newer versions" of the
original fldigi .deb package that is shipped with the main
distribution. The PPA packages replace all the files that that
the original package supplied.

No .deb found on Kamal's ppa repository (for fldigi or anything else) installs anything into /usr/local.

For future reference, your can list the internal contents of any .deb
file (to see what it installs and where) using "dpkg --contents".

This is a common configuration problem for new Linux users and one that Kamal has had to assist with many times.

"I've helped fldigi (and other package) users who have gotten
themselves into exactly that state. Invariably, after helping the
user locate and remove /usr/local/bin/fldigi, they say, 'Oh yeah, I remember installing that now!...'"

It is normal and proper that /usr/local/bin appears before /usr/bin in
$PATH (the standard default PATH comes that way in most Linux OS's).

If the user had previously installed their own build of fldigi to
/usr/local/bin (a common enough thing to do) then later forgets about
that and tries to use fldigi from either Kamal's PPA or from the main
distro, they "will not see" the newer /usr/bin/fldigi binary.